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Endocrinology > Lecture 2 > Flashcards

Lecture 2 Flashcards

1
Q

What are the 3 molecular classes of hormones?

A

1) amines
2) peptide/proteins
3) steroids

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2
Q

What are some examples of hormones in the amine category?

A

catecholamines
indoleamines
thyroid hormone

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3
Q

Catecholamines are derived from a single __________

A

tyrosine

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4
Q

Indolamines are derived from a single ___________

A

trypotophan

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5
Q

Thyroid hormone is derived from ____ _____________

A

2 tyrosines

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6
Q

What type of hormones have the shortest half life?

A

amines (2-3 minutes)

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7
Q

What is the half life of T4?

A

8 days

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8
Q

What is the half life of T3?

A

24 hours

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9
Q

What is the half life of proteins?

A

4-170 minutes

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10
Q

What is the half life of steroids?

A

minutes to several hours

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11
Q

Are catecholamines/indoleamines bound or free in the blood?

A

FREE (travel very quickly and are used rapidly)

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12
Q

How do catecholamines/indoleamines enact their signaling?

A

bind to membrane receptor to activate second messenger signaling

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13
Q

How do catecholamines/indoleamines enact their signaling?

A

bind to membrane receptor to activate second messenger signaling ALWAYS

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14
Q

What is the main difference between catecholamines and indoleamines?

A

SYNTHESIS

tyrosine - cat
tryptophan - indol

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15
Q

What are 3 catecholamines?

A

1) Dopamine
2) Norepinephrine
3) Epinephrine

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16
Q

What is the rate limiting step in catecholamine synthesis?

A

Tyrosine hydroxylase (used as a marker for dopaminergic activity)

catalyzes reaction of tyrosine to L-DOPA

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17
Q

Where does conversion of DOPA occur?

A

adrenal medulla

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18
Q

What is dopamine converted into?

A

NE and E (adrenaline)

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19
Q

What is the main endocrine function of dopamine?

A

INHIBIT prolactin release from the anterior pituitary

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20
Q

Dopamine neurons arise from the _________ _________ in the hypothalamus

A

arcuate nucleus

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21
Q

What are the 3 places in the brain where dopamine is made?

A

1) Substantia nigra
2) ventral tegmental area
3) arcuate nucleus of hypothalamus

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22
Q

In addition to the brain, where else is dopamine made?

A

adrenal medulla (where it is converted to NE)

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23
Q

True or false: dopaminergic neurons of the arcuate nucleus are always firing to tonically inhibit prolactin?

A

TRUE

always being released because tyrosine hydroxylase is tonically active

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24
Q

What enzyme catalyzes the conversion of dopamine to NE?

A

dopamine beta-hydroxylase

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25
Q

What leg of the ANS stimulates dopamine beta hydroxylase?

A

sympathetics

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26
Q

What type of neuron releases NE?

A

sympathetic post ganglionic

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27
Q

What innervates the adrenal medulla where conversion to NE occurs?

A

splanchnic nerves

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28
Q

Does NE act via alpha or beta adrenergic receptors?

A

BOTH

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29
Q

What cells the of the adrenal medulla release NE?

A

chromaffin cells (homologous to postsynaptic sympathetic neurons)

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30
Q

What cells the of the adrenal medulla release NE?

A

chromaffin cells (homologous to postsynaptic sympathetic neurons)

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31
Q

What is the rate limiting enzyme of indoleamine synthesis?

A

Tryptophan hydroxylase

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32
Q

What is an example of an indoleamine?

A

serotonin

33
Q

Where is serotonin made?

A

95% in the gut

5% raphe’s nucleus

34
Q

What does serotonin do?

A

act as a vasoconstrictor, stimulates smooth muscle contraction in intestine

35
Q

Where is serotonin made?

A

95% in the gut (ECCs)

5% raphe’s nucleus

36
Q

What does serotonin do?

A

act as a vasoconstrictor, stimulates smooth muscle contraction in intestine

37
Q

What is the molecular formula for tryptophan to melotonin?

A

tryptophan ——> serotonin —–> melotonin

38
Q

What is the rate limiting enzyme for serotonin to melatonin conversion?

A

N-acetyltransferase (SNA)

39
Q

Where is melatonin produced?

A

pineal gland

40
Q

What is the neurotransmitter in the brain that is referred to as the “happiness hormone”

A

Serotonin

41
Q

What is the molecular basis of SSRIs? (selective serotonin reuptake inhibitors)

A

increase concentration of serotonin at the synaptic cleft by BLOCKING reuptake so serotinin can sit in the cleft longer

42
Q

What is a complication with the logic of SSRIs?

A

lots of serotonin downregulates receptors so you cannot see effect of SSRIS - nothing to respond to increased amount of neurotransmitter in the cleft

43
Q

What enzyme catalyzes conversion of L-DOPA to dopamine?

A

Dopa decarboxylase

44
Q

What is the clinical importance of monoamine oxidase inhibitors? (MAO inhibitors)

A

catalyzes deamination of monoamines, increases dopamine (used in depression)

45
Q

What 2 classes of drugs enact monoamine inactivation?

A

1) DDC inhibitors (increase L-Dopa conc): Carbidopa and Benzerazide
2) COMT inhibitor (prevents inactivation and degradation of catecholamines): Entacpone
3) MAO inhibitors

46
Q

What is MAO and what does it do?

A

monoamine oxidase - catalyzes oxidative deamination of all monoamines

47
Q

What MAOs are present in humans?

A

MAOA and MAOB

48
Q

What effect does Entacapone have on dopamine

A

inhibits COMT (inhibits deactivation outside of cell)

49
Q

What effect does Carbidopa and Benzerazide have on dopamine?

A

inhibits conversion outside cell

50
Q

When is N-acetyltransferase active in the converting serotonin to melatonin?

A

during the night

51
Q

How does melatonin affect reproduction?

A

inhibits it! decreased spermatogenesis and testis size

52
Q

How is melatonin secretion regulated?

A

light info is conveyed to the SCN via the retinohypothalamic tract (RHT) which then the SCN transmits that info to the pineal gland

53
Q

Peptide hormones are transcribed as ______________

A

preprohormones

54
Q

Peptide hormones are transcribed as ______________

A

preprohormones

55
Q

Once the signal peptide is cleaved, a prohormone is formed which includes _________ and _______

A

hormone and copeptides

56
Q

Once the signal peptide is cleaved, a prohormone is formed which includes _________ and _______

A

hormone and copeptides

57
Q

What has a longer half life, hypothalamic or pituitary hormones?

A

Pituitary

58
Q

What hormone has the longest half life?

A

IGF-1

59
Q

Steroids are all derived from __________ precursor

A

cholesterol

60
Q

What is the central precursor which forms all steroid hormones?

A

Pregnenolone (forms aldosterone, cortisol, estrogens/androgens)

61
Q

What is responsible for carriage of cholesterol from the outer mitochondria to the inner?

A

StAR

62
Q

What is the main endocrine axis?

A

HPA (hypothalamic - pituitary)

hormones can regulate any part of axis)

63
Q

Short loop feedback is from _______ to _______

A

pituitary to hypothalamus

64
Q

Long loop feedback is from __________ to __________

A

endocrine to hypothalamus

65
Q

Long loop feedback is from __________ to __________

A

endocrine to hypothalamus

66
Q

What are the 4 examples of positive feedback systems in the human body?

A

1) Partuition (more contractions, more oxytocin until birth stops)
2) Lactation (more suckling, more oxytocin until baby stops feeding)
3) Ovulation (LH stimulates estradiol which stimulates more LH until oocyte is released)
4) Blood clotting (tissue injury activates platelets which activate more platelets until clotting stops)

67
Q

What is the only NON-reproductive positive feedback?

A

blood clotting

68
Q

What is the only NON-reproductive positive feedback?

A

blood clotting

69
Q

What is the HPA flow for T3/T4 hormones?

A

TRH (hypo) –> TSH (ant. pit.) –> T4/T3

70
Q

What is a primary thyroid problem?

A

problem with T4/T3 secretion

71
Q

Where is a secondary thyroid problem?

A

pituitary (TSH secretion)

72
Q

Where is the problem in a tertiary thyroid problem?

A

hypothalamus

73
Q

How would you diagnose a secondary thyroid problem?

A

Undetectable TSH and unresponsive to TRH

74
Q

What is euthyroid sick syndrome?

A

normal TSH and thyroid but low T4/T3 (hypothyroid symptoms)

75
Q

What hormone is looked at to assess heart failure?

A

BNP

76
Q

Which heart hormone has a longer half life?

A

BNP

77
Q

What do ANP and BNP do?

A

promote water shedding - opposite effect of AVP and aldosterone

78
Q

What do ANP and BNP do?

A

promote water shedding - opposite effect of AVP and aldosterone

79
Q

Do women or men have higher ANP and BNP?

A

women (increases with age)

Endocrinology (16 decks)

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